As for why they were in hiding and did not reveal the truth to the world, the answer was very simple.
Because humans needed to move forward under a lie.
Not everyone could withstand despair.
Knowing that human civilization was on the verge of destruction and was very likely to be destroyed by domain factions, many people would definitely choose to give up struggling and degrade themselves.
Only by giving the world hope could everyone advance under the halo of hope.
If what was presented was despair, even many geniuses would lose their expectations for the future and choose to give up on themselves.
Even if the human forces hiding in the dark and silently working for the future of humanity knew the truth, they would not expose this lie.
Apart from not being able to fight a domain faction head-on, the most important thing was still the word "hope".